Casting magnesium and alloys thereof



March 18, 1930. J E. H QY 1,75L03s CASTING MAGNESIUM AND ALLOYS THEREOF Filed July 5. 1926 l N VEN TOR.

' 75571 f. J Oy- Patented Mar. 18, 1930 UNITED" sTATEs I PATENT OFFICE 191m m nor,

OF MIDLAND, MICHIGAN, ASSIGNOR TO THE DOW CHEMIGAL COMPANY,

- OF MIDLAND, MICHIGAN, A CORPORATION OF MICHIGAN 'oas'rme mennsmm AND armors Tnmmor Application filed July 3,

- molten state magnesium or an alloy largely composed of this metal are well known and thesedifliculties are still present when it is v attempted to introduce such metal into a mold in any process of casting. For ex- 1 am le, when sand castings are made in the or ary way by simply pouring theinolten magnesium or light alloy metal in thesand mold, there is a very pronounced tendency for the metal to burn in the sprue. Even ifthe burning is not serious enough to prevent the cast article from being properly finished when removed from the mold",- a certain loss of metal,-due to oxidation, is inevitable, and of course the cleaner the casting, the more easily maiy the finishin operation be carried out.

t has hereto ore been proposed to overcome these difliculties specifically in casting magnesium and alloys containing-the sam'e by dustin the mold prior to casting the metal with sulp ur or eqmvalent material capable of giving ofi in contact with the molten metal a vapor whlch is more easily oxidizable than magnesium. This procedure, however, has

V V taken on 'a plane indicated by line II I-III, rectlyto gauge the 'amountof sulphur or the objection that it is obviously difiicult'corequivalent material thus used, and particularly if an excess is applied to the surface" elther of the mold proper or the core, so

much vapor may be generated that some of 49 1t becomes entrap ed during the the metal is solidi 'ng, the result emg blow holes or surface shrinks in the casting, Fur

. thermore, the sulphur or equivalent material hasto be ap lied or dusted onto the mold so that the 111 0d in question is obviously not riod that" 1926. Serial No. 120,4e.

applicable where a metal mold is employed,

because of the non-porous character of the latter.

The present improved. method has as its object to generate directly in the mold cavity a gas that is inert toward the metal being cast, and s ecifically sulphur dioxide, man

amount su cient to displace the air normally filling such bavity but without danger of sulphur vapor becoming. entrapped and generatmg. an excessive amount of gas at some point.

My improved method further permits of the conven ent re phur dioxide or example, that isthus introduced into. or supplying to the mold cavity.

So that there will be no unnecessary wastage on the one hand or insuificient amount of gas generated, on theother hand.

To the accomplishment of of the steps hereinafter fully described and particularly annexed drawing tion setting forth in detail certain means and mode of'carrying out the invention, such dislation of the amount of sul I the foregoing V and related ends, the invention, then, consists pointed out in the claims, the I and the following descripclosed means and mode illustrating, however,

but one of various ways in which the principle of the invention may be used.

. In said annexeddraWingzp Fig. 1 is a central vertical section thru a mold constructed and arrangedto carry out my improved method; Fig. 2 is a broken top plan view of the same; and Fig. 3 is a section F g.1}. v e mold thus illustrated is specifically designed for casting a piston for aninternalj combustion engine or like-hollow article ofcast and an enlargedspace 3 continuous with the upper end of such cavity whereby a lateral ofiset shoulder 4 is provided that encircles such cavity.

. The core 6, which may be either of sand or of collapsible metalvparts, is of course separable from the mold 1 and is formed with an enlargement 7 at its upper end adapted to fit the enlarged portion 3 of the mold cavity the shoulder 8 between such enlargement and the core proper resting on the offset 4 in the mol when the parts are assembled.

' The enlargement 7 and such shoulder of the core or else the complementary portions of the mold 1 are so formed 'as to leave vent holes 9 thru which air or other gases may escape from the mold cavity, when the .casting is poured. For the purpose of introducing the molten metal, the core is provided with a central sprue 11, the lower portion of which communicates'thru a gate 12 with the mold .cavity'in which the casting is .to be formed.

ticularly desirab e where such part is of metal, the core is placed in. such mold in "the conventional wa Thereupon, the spoon 12 is inserted into t e sprue so as to occupy a portion in the lower end thereof as illustrated in Fig. '1, such spoon having had previously placed therein a quantity ,of burning sul hur or of sulphur which is subsequently ign ted before .the spoon is thus introduced into the sprue. Upon being left to stand for a few seconds, the sulphur will consume oxyof the sulphur. 1n the'sprue is expelled forgen in,the air confined in the. mold cavit and at the same time more or less fill suc cavity with sul hur dioxide, it being noted that the sprue f ieely communicates with the main cavity thru the gate 12. When ready to pour the metal, the spoon is removed and "the 'heavy gas nera'ted by the combustion cibly into the mold cavity, finally esca ing thru the vents,9(i which as explained a ove crate a suitable inert gas, paradichlor nare so constructe as to 'ass around thecore, and which are of suita le size-that molten metal will solidify or freeze therein instead.

of Xfiassing entirely thru. v an example of amaterial that will n- 201 may be named, altho/thismaterial has the "disadvantage that the 'ases generated. are

more obnoxious' than t e. sulphur dioxide handle a quantity of burning sulsurface.

formed by burning sulphur, as also na hthalene, carbon tetrachloride and fuel 011. In no case, however,'does the material used thus to generate the gas in question come into direct contact with the surfaces of the mold parts that define the casting. There 1s, accordingly no danger of an excessive amount of such gas being generated with resultant formation of blow holes or surface shrinks.-

Other modes of applying the principle of my invention may beemployed instead of theme explained, change being made as regards'the ap aratusand the process or method herein isclosed, providedthe means or steps stated by any of the following-claims or'the equivalent of such stated means or steps be employed. I

"I therefore particularly point out and distinctly claim as my invent1on: g

1. A method of casting a readily oxidizable metal or an alloy containing the same, which com rises eliminatin oxygen from 'the path 0 the molten meta on. its way to andwithin the mold cavity'by ignitingian oxygen-consuming material in the pat of the nietal and out of contachwith' themold 2. A method of casting a readily oxidizable metal or an alloy containing the same, which com rises eliminatin oxygen from the. path 0 the molten meta on its way to and within the mold cavity by igmting a. sulphur-containing material in the path of the metal and outof-contact with the mold surface. v

3. In a method of casting alreadilyl oxidizable-metal or an alloy containing t 9 same, the steps which consist in eliminating air from the mold cavity and the pouring nlet thereto as well, by supporting in the inlet. a quantity of material capable of generating a gas inert toward the metal being cast, an treating such material to generate such as.

4. 'In a method of'casting a readil 0x1 able metal or an alloy containing t e same, no the steps which consist in eliminating air from the mold cavity and the pouring nlet thereto, as well, by supportlngiln the inlet aquantity of-sul hur, and. igniting such sulphur, whereby tially filled wlthsulphur vapor and sulphur dioxide.

5. In apparatus for casting a readily oxidizable metal or alloy thereof, the combination with a mo ld including a core formed 12 0 t 'e mold cavity is substangenerating material supported from said closure. I I 7 In apparatus for casting a readily oxidizable metal or alloy thereof, the combination with a mold including a. core formed with a sprue having a gate to the mold cavity proper,'0f a removable closure for the upper end of said sprue, and a container adapted to receive and hold a quantit of burning sulgahur supported from said 0 osure.

igned by me this 22nd dafilgf June, 1926.

I J O E. HOY. 

